radiation
noun
ra·di·a·tion
ˌrā-dē-ˈā-shən 
1
a
: the action or process of radiating
b
: the process of emitting radiant energy in the form of waves or particles
c(1)
: the combined processes of emission, transmission, and absorption of radiant energy
(2)
: the transfer of heat by radiation compare conduction, convection
2
a
: something that is radiated
b
: energy radiated in the form of waves or particles
3
: radial arrangement
Examples of radiation in a Sentence
She was exposed to high levels of radiation.
He goes in for radiation next week.
the sun's radiation of heat
Recent Examples on the Web
Another unresolved issue is that primordial black hole formation may require intense bursts of high-energy radiation—and no such source has yet been identified near QSO1.
—
Rupendra Brahambhatt, Interesting Engineering, 3 Jan. 2026
Gopie said the radiation had new side effects, including intense headaches and a burning feeling in her skin.
—Kerry Breen, CBS News, 3 Jan. 2026
Other long-running missions at Mars are also producing critical datasets for understanding radiation hazards, scientists said.
—Sharmila Kuthunur, Space.com, 31 Dec. 2025
At such distances, the astronauts will face a far harsher radiation environment than do the vast majority of space travelers.
—Jackie Wattles, CNN Money, 31 Dec. 2025
See All Example Sentences for radiation
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Rupendra Brahambhatt, Interesting Engineering, 3 Jan. 2026
Gopie said the radiation had new side effects, including intense headaches and a burning feeling in her skin.
—Kerry Breen, CBS News, 3 Jan. 2026
Other long-running missions at Mars are also producing critical datasets for understanding radiation hazards, scientists said.
—Sharmila Kuthunur, Space.com, 31 Dec. 2025
At such distances, the astronauts will face a far harsher radiation environment than do the vast majority of space travelers.
—Jackie Wattles, CNN Money, 31 Dec. 2025
See All Example Sentences for radiation
Cite this Entry
“Radiation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radiation. Accessed 6 Jan. 2026.
Copy CitationKids Definition
radiation
noun
ra·di·a·tion
ˌrād-ē-ˈā-shən
1
: the action or process of radiating
especially
: the process of giving off radiant energy in the form of waves or particles
2
: something that is radiated
especially
: energy radiated in the form of waves or particles
Medical Definition
radiation
noun
ra·di·a·tion
ˌrād-ē-ˈā-shən
1
: energy radiated in the form of waves or particles
2
3
: a tract of nerve fibers within the brain
especially
: one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei
the optic radiations
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